Understanding the shape of a borehole and the placement of a casing inside the borehole are important for the maintenance of well integrity. Acoustic calipering techniques and systems can map casing placement inside the borehole to aid in attaining this understanding. However, available acoustic systems are typically mounted inside the casing and, as such, are isolated from annular regions between a casing string and formation. Therefore, available acoustic systems cannot detect many conditions that would be of interest to an operator during or after cementation processes when operators place cement in the annular regions.